This application claims benefit of priority to Japanese Patent Application No. 11-258887 filed Sep. 13, 1999, the entire content of which is incorporated by reference herein.
1. Field of the Invention
This invention relates to a control apparatus for ventilating a tunnel that operates ventilators in a tunnel so as to keep visibility for drivers within a satisfactory range. The visibility, for example, represents air pollution density in the tunnel.
2. Discription of the Background
Concerning a road tunnel for automobiles, it is essential to control air pollution density to be within a satisfactory range and to keep visibility for drivers well from the point of view of guaranteeing drivers"" safety and comfortableness.
In general, a ventilator, that may include a blower, an exhauster, a jet fan, a dust chamber or the like, is set in a tunnel, and a control apparatus is provided for operating the ventilation system efficiently according to the air pollution density.
There are several kinds of control systems that operate the ventilator. FIG. 1 is one example of a conventional control system. FIG. 1(a) is a schematic view showing one example of the installation of ventilation equipment in a tunnel. FIG. 1(b) is a block diagram of a conventional control apparatus.
The ventilation equipment includes a TC(Traffic Counter) sensor 51 that measures speeds of automobiles traveling on a road and the number of automobiles, and distinguishes between small cars and large-sized cars, a VI(Visibility Index) sensor 52 that measures a VI value in the tunnel, a CO(Carbon monoxide) sensor 53 that measures carbon monoxide density in the tunnel, an AV(Wind velocity) sensor that measures a wind direction and a wind velocity in the tunnel, and a ventilator 55 having jet fans or the like. The VI value is an index that represents visibility in the tunnel. Where the VI value indicates 100%, the visibility is completely clear. Where the VI value indicates 0%, it means completely dark.
The control apparatus, as shown in FIG. 1(b), includes a traffic volume predictor 56 that predicts the volume of traffic in the tunnel in a fixed cycle on the basis of an output of measured traffic value from the TC sensor 51, a ventilation-planning setter 57 that calculates a working plan value representing the amount of work to be done by the ventilator 55 on the basis of the predicted traffic value, and a ventilation feedback controller 58.
To put it concretely, the TC sensor 51 counts the number of automobiles in a cycle of one hour. The traffic volume predictor 56 accumulates the number of automobiles output from the TC sensor 51 and makes out a one-day traffic pattern for small cars and a one-day traffic pattern for large-sized cars separately. The traffic patterns are classified into several classes, for example, a weekday, the day before holiday, a holiday, the day after holiday and the like, and then averaged in the respective classes, thereby making basic traffic patterns in the respective classes. In case of estimating the amount of traffic in this state, the predicted traffic value is determined by adjusting the basic traffic pattern that corresponds to the day to be estimated in light of a change of the traffic on that day.
The ventilation-planning setter 57 estimates the amount of pollutant and the ability to ventilate in the next cycle on the basis of the predicted traffic value that is obtained from the traffic volume predictor 56, and calculates the working plan value needed for controlling visibility and air pollution density to be within a satisfactory range in the next cycle. The working plan value becomes the basis for determining the amount of work to be done by the ventilator 55 in the next cycle.
The ventilation feedback controller 58 calculates a feedback control value, which is also needed for controlling visibility and air pollution density to be within a satisfactory range in the next cycle, on the basis of the VI value from the VI sensor 52, the carbon monoxide density from the CO sensor 53, the wind direction and the wind velocity from the AV sensor 54, and outputs the feedback control value to a plan/feedback cooperation controller 59.
The plan/feedback cooperation controller 59 cooperates between the working plan value from the ventilation-planning setter 57 and the feedback control value from the ventilation feedback controller 58, and determines an operation command for the ventilator 55. The ventilator 55 is controlled on the basis of the operation command.
There has been another control system for ventilating a tunnel that uses only a feedback control for middle-sized tunnels as shown in FIG. 2.
As described above, the control apparatus controls to keep the VI value and the carbon monoxide density within a satisfactory range by controlling the ventilator 55 in consideration of drivers"" safety and comfortableness.
Since it is generally known that the carbon monoxide density can be kept much lower than a permissible value by controlling the VI value to be within a satisfactory range, the VI value is the most important control index for ventilating tunnels.
The VI sensor 52 includes a light-projector and a light-interceptor, and the light-projector and the light-interceptor are disposed at intervals of 100 meters, thereby measuring an attenuation rate of a laser beam radiated from the light-projector at the time that the laser beam reaches to the light-interceptor.
In the conventional control apparatus, the attenuation rate measured by the VI sensor 52 is used as an index that represents visibility for drivers. However, there are some following problems.
(1) The VI sensor 52 is disposed near a wall of the tunnel, which does not match the actual situation. Because, a portion that visibility should be kept well for drivers is not by the wall, but a portion that is about one meter apart from a road on which drivers are traveling.
(2) An attenuation rate of a laser beam is used as an index that represents visibility for drivers. However, the attenuation rate does not directly correspond to visibility for drivers.
(3) A range that the VI sensor may measure a VI value is limited to an area at which the VI sensor is disposed. Accordingly, in order to measure the VI values throughout a tunnel, a large number of VI sensors are required. As a result, it is very difficult to realize such system due to an increase in installation costs.
(4) With regard to the TC sensor 51, there are several types of TC sensors as described below. But they have their own problems.
a. Ultrasonic waves type
An ultrasonic generating and receiving apparatus emits an ultrasonic wave toward around a road surface intermittently and receives the reflected wave from automobiles or the road surface. The ultrasonic apparatus detects the existence of automobiles by comparing the reflected waves from automobile and the road surface.
b. Optical type
An infrared light generating and receiving apparatus emits an infrared light toward around a road surface and receives the reflected light from automobiles or the road surface. The infrared light apparatus detects the existence of automobiles by comparing the reflected lights from the automobile and the road surface.
c. Loop coil type
A loop coil is laid under a road that automobiles are traveling. The existence of automobiles is detected by means of current flowing into the loop coil at the time that automobiles pass over the loop coil.
In these TC sensors, the existence of automobiles is detected by means of changes of ultrasonic waves, infrared lights or current of the loop coil, and the TC sensors also distinguish between small cars and large-sized cars at the same time.
However, there is a possibility that these TC sensors may detect as a large-sized car or count the number of automobiles erroneously, in case that two small cars travel continuously.
With regard to a tunnel in the mountains, since fog flows into the tunnel, visibility sometimes worsens. In this case, it is difficult for the conventional TC sensors to distinguish between exhaust gas and fog. That is, the TC sensors may not distinguish which of exhaust gas or fog makes the visibility worse. In general, visibility is improved by letting the outside air into the tunnel. Accordingly, in case that a deterioration of visibility results from the fog, the visibility may worsen.
Since the above-mentioned control apparatus may not fully grasp the actual condition of the tunnel, a ventilation control may delay, resulting in deterioration of visibility and air pollution density. On the other hand, the ventilator may be used more than is necessary, thereby increasing a waste of electricity.
Accordingly, one object of this invention is to provide a control apparatus for ventilating a tunnel that may grasp the actual condition of the tunnel and improve drivers"" safety and comfortableness.
Another object of this invention is to provide a control apparatus for ventilating a tunnel that may save in electricity for a ventilator.
The present invention provides a control apparatus for a ventilator that ventilates a tunnel in response to visibility of the inside of the tunnel, including at least one picture image input device configured to take a picture of the inside of the tunnel, a visibility index determination device configured to determine a visibility index value on the basis of a picture image data of the picture taken by the picture image input device in light of a table representing a relationship between the picture image data and the visibility index value, a feedback controller configured to calculate an operation command for operating the ventilator on the basis of a feedback control value calculated by comparing the visibility index value with a target value of the visibility index value.